Light weight high temperature well cement compositions and methods

ABSTRACT

The present invention provides light weight high temperature well cement compositions and methods. The compositions are basically comprised of calcium aluminate, ASTM class F fly ash and water.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No.08/912,203, filed Aug. 15, 1997 U.S Pat. No. 5,900,053.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to light weight high temperaturewell cement compositions and methods, and more particularly, to suchcompositions and methods which are suitable for cementing hightemperature wells containing carbon dioxide.

2. Description of the Prior Art

In the completion of high temperature subterranean wells containingcarbon dioxide, eg., geothermal wells, the use of conventional hydrauliccement compositions often results in early well failure. Because of thehigh static well bore temperatures involved coupled with the presence ofbrines containing carbon dioxide, conventional hydraulic well cementsrapidly deteriorate due to alkali carbonation, especially sodiumcarbonate induced carbonation. In geothermal wells which typicallyinvolve very high temperatures, pressures and carbon dioxideconcentrations, conventional well cement failures have occurred in lessthan five years causing the collapse of the well casing.

It has heretofore been discovered that a cement material known ascalcium phosphate cement formed by an acid-base reaction between calciumaluminate and a phosphate-containing solution has high strength, lowpermeability and excellent carbon dioxide resistance when cured inhydrothermal environments. However, calcium phosphate cement has arelatively high density, eg., a density in the range of from about 15 toabout 17 pounds per gallon, which is too high for geothermalapplications. That is, in geothermal wells the hydrostatic pressureexerted by the high density calcium phosphate cement often exceeds thefracture gradients of subterranean zones penetrated by the well borewhich causes the formation of fractures into which the cement is lost.While calcium phosphate cements have been developed which include hollowmicrospheres and as a result have densities of about 10 pounds pergallon, such light weight compositions are relatively expensive and thepresence of the microspheres in the cured cement reduces its compressivestrength.

Thus, there is a need for improved less expensive well cementcompositions useful in cementing high temperature wells containingcarbon dioxide.

SUMMARY OF THE INVENTION

The present invention provides improved cement compositions and methodswhich meet the needs described above and overcome the deficiencies ofthe prior art. The compositions are particularly useful in hightemperature wells containing carbon dioxide such as geothermal wells. Acomposition of the present invention is basically comprised of calciumaluminate, fly ash and sufficient water to form a pumpable slurry.

Another composition of this invention is comprised of calcium aluminate,fly ash, sufficient water to form a pumpable slurry, a foaming agent, afoam stabilizer and a gas sufficient to form a foam having a density inthe range of from about 9.5 to about 14 pounds per gallon.

Yet another composition of this invention is comprised of calciumaluminate, sodium polyphosphate, fly ash, sufficient water to form apumpable slurry, a foaming agent, a foam stabilizer and a gas present inan amount sufficient to form a foam having a density in the range offrom about 9.5 to about 14 pounds per gallon.

The methods of the present invention for cementing a high temperaturesubterranean zone containing carbon dioxide penetrated by a well borebasically comprise the steps of forming a well cement composition ofthis invention, pumping the cement composition into the subterraneanzone by way of the well bore and allowing the cement composition to setinto a hard impermeable mass therein.

It is, therefore, a general object of the present invention to providelight weight high temperature well cement compositions and methods.

A further object of the present invention is the provision of improvedcarbonation resistant well cement compositions and methods.

Other and further objects, features and advantages of the presentinvention will be readily apparent to those skilled in the art upon areading of the description of preferred embodiments which follows.

DESCRIPTION OF PREFERRED EMBODIMENTS

As mentioned above, high temperature wells containing carbon dioxidesuch as geothermal wells generally require the use of well cementcompositions which do not deteriorate in the presence of carbon dioxidecontaining brines. The term "high temperature" is used herein to meanwells wherein the static bottom hole temperature is above about 300° F.up to as high as about 700° F. When conventional hydraulic cements areutilized in such wells, carbonation causes dissolution of the cementwhich is converted into water-soluble salts. Further, severe corrosionof steel pipe takes place thereby resulting in the total disruption ofthe conventional cement supported well structure.

When conventional normal density cement slurries are utilized ingeothermal and other similar wells, loss of circulation problems areoften encountered. This is due to the weak unconsolidated formations inthe wells having very low fracture gradients. When a relatively highdensity cement slurry is pumped into such a well, the hydrostaticpressure exerted on the weak unconsolidated subterranean zones thereincauses the zones to fracture. This in turn causes the cement slurrybeing pumped to enter the fractures and lost circulation problems tooccur. To avoid such problems, the cement compositions utilized ingeothermal and other similar wells must be of light weight, i.e., havedensities in the range of from about 9.5 to about 14 pounds per gallon.

By the present invention, improved well cement compositions are providedwhich resist high temperature carbonation deterioration. A cementcomposition of this invention which can be non-foamed or foamed isbasically comprised of calcium aluminate, fly ash and sufficient waterto form a pumpable slurry. When foamed, the cement composition includesa foaming agent, a foam stabilizer and a gas present in an amountsufficient to form a foam having a density in the range of from about9.5 to about 14 pounds per gallon.

Another composition of this invention is comprised of calcium aluminate,sodium polyphosphate, fly ash, a foaming agent, a foam stabilizer and agas present in an amount sufficient to form a foam having a density inthe range of from about 9.5 to about 14 pounds per gallon.

The calcium aluminate can be any commercial grade calcium aluminatesuitable for use as a cement. A suitable such calcium aluminate iscommercially available from the Lehigh Portland Cement Company ofAllentown, Pennsylvania, under the trade designation "REFCON™." Thecalcium aluminate is generally included in the cement composition in anamount in the range of from about 15% to about 45% by weight of thecomposition.

When used, the sodium polyphosphate includes sodium hexametaphosphateand sodium triphosphate as well as vitreous sodium phosphates. Asuitable sodium polyphosphate for use in accordance with the presentinvention is commercially available from Calgon Corporation ofPittsburgh, Pa. The sodium polyphosphate can be included in the cementcomposition in an amount in the range of from about 5% to about 20% byweight of the composition. When included, the sodium polyphosphatecombines with the calcium aluminate to form calcium phosphate in theform of hydroxyapatite.

Fly ash is the finally divided residue that results from the combustionof ground or powdered coal and is carried by the flue gases generated. Aparticular fly ash that is suitable in accordance with the presentinvention is a fine particle size ASTM class F fly ash having a Blainefineness of about 10,585 square centimeters per gram which iscommercially available from LaFarge Corporation of Michigan under thetrade designation "POZMIX™." Another fly ash that is suitable is an ASTMclass F fly ash which is commercially available from Halliburton EnergyServices of Dallas, Texas under the trade designation "POZMIX™ A." Thefly ash is generally included in the composition in an amount in therange from about 25% to about 45% by weight of the composition.

The major crystalline phase of ASTM class F fly ash is mullite (3Al₂O₃.2SiO₂). It reacts with calcium aluminate to form calcium aluminosilicate (CaO.Al₂ O₃.2SiO₂). Also, iron and quartz in the fly ash reactwith the calcium aluminate to form andradite (Ca₃ Fe₂ SiO₄)₃. Thesereactions increase the compressive strength of the set cement ascompared to set calcium aluminate cement alone.

The water utilized can be from any source provided it does not containan excess of compounds that adversely affect other compounds in thecement composition. For example, the water can be fresh water orsaltwater. Generally, the water is present in the cement composition inan amount sufficient to form a pumpable slurry, i.e., an amount in therange of from about 10% to about 60% by weight of the composition.

In order to facilitate the foaming of the cement composition, a foamingagent is included in the composition. A particularly suitable andpreferred such foaming agent is an alpha-olefinic sulfonate having theformula

    H(CH.sub.2).sub.n --CH═CH--(CH.sub.2).sub.m SO.sub.3 Na

wherein n and m are individually integers in the range of from about 6to about 16. The foaming agent is generally included in the cementcomposition in an amount in the range of from about 1% to about 2% byweight of the water in the composition. The most preferred foaming agentof this type is an alpha-olefinic sulfonate having the above formulawherein n and m are each 16, i.e., a sulfonic acid C₁₆₋₁₆ alkane sodiumsalt.

A foam stabilizer is also included in the cement composition to enhancethe stability of the composition after it is foamed. A particularlysuitable and preferred stabilizing agent is an amidopropylbetaine havingthe formula

    R--CONHCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub.2 CH.sub.2 CO.sub.2.sup.-

wherein R is a radical selected from the group of decyl, cetyl, oleyl,lauryl and cocoyl. The foam stabilizer is generally included in thecement composition in an amount in the range of from about 0.5% to about1% by weight of the water in the composition. The most preferred foamstabilizer of this type is cocoylamidopropylbetaine.

The gas utilized to foam the composition can be air or nitrogen, withnitrogen being the most preferred. The amount of gas present in thecement composition is that amount which is sufficient to form a foamhaving a density in the range of from about 9.5 to 14 pounds per gallon,most preferably 12 pounds per gallon.

In order to provide resiliency to the set cement composition of thisinvention, the composition may optionally include inert ground rubberparticles. Such particles are produced from worn out tires and arecommercially available from Four D Corporation of Duncan, Okla.

At static well bore temperatures above about 125° F., a set retarder isrequired. The set retarder functions to lengthen the time in which thecement composition starts to thicken and set so that the composition canbe pumped into the well bore and into the zone to be cemented beforesuch thickening takes place. Preferred such set retarders for use inaccordance with this invention are gluconic acid and citric acid. Whenused, the set retarder is included in the cement composition in anamount in the range of from about 0.5% to about 2% by weight of thecomposition.

A preferred composition of the present invention is comprised of calciumaluminate present in an amount of about 30% by weight of thecomposition, ASTM class F fly ash present in an amount of about 50% byweight of the composition and water present in an amount sufficient toform a slurry.

Another preferred composition of the present invention is comprised ofcalcium aluminate present in an amount of about 30% by weight of thecomposition, ASTM class F Fly Ash present in an amount of about 50% byweight of the composition, sufficient water to form a pumpable slurry, afoaming agent comprised of a sulfonic acid C₁₆₋₁₆ alkane sodium saltpresent in an amount of about 1.5% by weight of the water in thecomposition, a foam stabilizer comprising cocoylamidopropyl-betainepresent in an amount of about 0.75% by weight of the water in thecomposition and a gas present in an amount sufficient to form a foamhaving a density in the range of from about 9.5 to about 14 pounds pergallon.

Yet another preferred composition of this invention is comprised ofcalcium aluminate present in an amount of about 28% by weight of thecomposition, sodium polyphosphate present in an amount of about 19% byweight of the composition, ASTM class F fly ash present in an amount ofabout 49% by weight of the composition, sufficient water to form apumpable slurry, a foaming agent comprised of a sulfonic acid C₁₆₋₁₆alkane sodium salt present in an amount of about 8% by weight of thewater in the composition, a foam stabilizer comprisingcocylamideopropylbetaine present in an amount of about 4% by weight ofthe water in the composition and a gas present in an amount sufficientto form a foam having a density in the range of from about 9.5 to about14 pounds per gallon.

As previously mentioned, the above described cement compositions caninclude ground rubber particles present in an amount in the range offrom about 10% to about 40% by weight of the compositions to improve theresiliency of the compositions. Further, when the static well boretemperature is above about 125° F., a set retarder selected from thegroup of gluconic acid and citric acid is included in the cementcompositions in an amount of about 1.0% by weight of the compositions.

The cement compositions of this invention may be prepared in accordancewith any of the mixing techniques utilized in the art. In one preferredmethod, a quantity of water is introduced into a cement blender followedby the sodium polyphosphate (if used), calcium aluminate and fly ash.The mixture is agitated for a sufficient period of time to form apumpable non-foamed slurry.

When the cement slurry formed as above is foamed, the slurry is pumpedto the well bore and the foaming agent and foam stabilizer followed bythe gas utilized are injected into the slurry on the fly. As the slurryand gas flow through the well bore to the location where the resultingfoamed cement composition is to be placed, the cement composition isfoamed and stabilized. Other liquid additives utilized, if any, areadded to the water prior to when the other components of the cementcomposition are mixed therewith and other dry solids, if any, are addedto the water and cement prior to mixing.

The methods of this invention of cementing a high temperaturesubterranean zone containing carbon dioxide penetrated by a well boreare basically comprised of the steps of forming a foamed cementcomposition of this invention, pumping the foamed cement compositioninto the subterranean zone to be cemented by way of the well bore andthen allowing the foamed cement composition to set into a hardimpermeable mass therein.

In order to further illustrate the improved cement compositions andmethods of this invention, the following examples are given.

EXAMPLE 1

In a controlled test, API Class G Portland Cement was mixed with 40%silica flour and water to form a cement slurry. The slurry was allowedto set for 24 hours at a temperature of 190° F. Thereafter, the setcement was placed in an aqueous 4% by weight sodium carbonate solutionfor 28 days at 600° F.

A calcium phosphate cement composition was prepared comprised of 23.3%water; 17.5% calcium aluminate; 15.6% sodium polyphosphate; 40.8% ASTMclass F fly ash, 1.9% sulfonic acid C₁₆₋₁₆ alkane sodium salt foamingagent and 0.9% cocoylamidopropylbetaine foam stabilizer, all by weightof the composition. After mixing, the resulting slurry was allowed toset for 24 hours at a temperature of 190° F. Thereafter, the set cementwas placed in a 4% by weight aqueous sodium carbonate solution for 28days at 600° F.

At the end of the test periods, samples from the interiors of the setPortland Cement composition and calcium aluminate cement compositionwere tested. The tests showed that the Portland Cement compositioncontained 1.5% by weight calcium carbonate and the calcium phosphatecement contained none. Samples were also tested taken from the exteriorsof the set cements which showed that the Portland cement compositioncontained 10.6% calcium carbonate while the calcium phosphate cementcontained none.

EXAMPLE 2

Test calcium phosphate cement slurry samples were prepared by mixing 240grams of water with 180 grams of calcium aluminate, 160 grams of sodiumpolyphosphate and 420 grams of fly ash for each sample. Various Portlandcement set retarding additives were combined with the test samples.After mixing, each test sample was tested for thickening time at 125° F.in accordance with the test procedure set forth in API Specification ForMaterials And Testing For Well Cements, API Specification 10, 5th ed.,dated Jul. 1, 1990 of the American Petroleum Institute. The setretarders tested are identified and the thickening time test results areset forth in Table 1 below.

                  TABLE I                                                         ______________________________________                                        Thickening Time Tests.sup.1                                                                     Amount Added to                                                                            Thickening Time                                  Set Retarder Tested Test Sample, grams hrs.:mins.                           ______________________________________                                        None          --           1:35                                                 Acrylic Acid Polymer 6 2:02                                                   Tartaric Acid 6 1:12                                                          Gluconic Acid 6 4:05                                                          Citric Acid 6  6:00+                                                        ______________________________________                                         .sup.1 API Tests at 125° F.                                       

From Table I, it can be seen that gluconic acid and citric acid are themost effective set retarders for the calcium aluminate cementcomposition at a temperature of 125° F.

EXAMPLE 3

Two additional calcium aluminate cement slurry samples were prepared asshown in Table II below. After mixing, the resulting slurries wereallowed to set for 24 hours at 190° F. Thereafter, the set samples wereplaced in 4% by weight aqueous sodium carbonate solutions for 28 days at600° F. At the end of the 28 day periods, the samples were tested forcompressive strengths in accordance with the above mentioned APISpecification 10. The results of the tests are also set forth in TableII below.

                                      TABLE II                                    __________________________________________________________________________    Compressive Strength Tests                                                        Sample Components, grams         Compressive                              Sample  Calcium                                                                             Sodium                                                                              Fly                                                                              Foaming                                                                            Foam Density                                                                           Strength,                                  No. Water Aluminate.sup.1 Phosphate.sup.2 Ash.sup.3 Agent.sup.4                                                  Stabilizer.sup.5 lb/gal. psi             __________________________________________________________________________    1   465.5                                                                             350   311.5 815.5                                                                            37.3 18.6 12.1                                                                               570                                       2 266 200 178 466 21.3 10.6 15.1 1060                                       __________________________________________________________________________     .sup.1 "REFCON ™" from Lehigh Portland Cement Co.                          .sup.2 Calgon Sodium Polyphosphate                                            .sup.3 ASTM class F fly ash from LaFarge Corp.                                .sup.4 Sulfonic acid C.sub.16--16 alkane sodium salt                          .sup.5 Cocoylamidopropylbetaine                                          

From Table II, it can be seen that the calcium aluminate cementcompositions of the present invention maintained their compressivestrengths after 28 days in the presence of sodium carbonate solutions at600° F.

EXAMPLE 4

An API Class G Portland cement was mixed with 40% silica flour and waterto form a cement slurry. The slurry was allowed to set for 48 hours at atemperature of 500° F. Thereafter, the set cement was placed in anaqueous solution containing 2.4% dry ice and 0.8% sulfuric acid. Acalcium aluminate cement composition was prepared comprised of 30%water, 37% calcium aluminate and 33% ASTM class F fly ash. The resultingslurry was allowed to set for 48 hours at a temperature of 500° F.Thereafter, the set cement was placed in an aqueous solution containing2.4% dry ice and 0.8% sulfuric acid. The above described test cementsamples were kept in the carbonate-acid solutions for 53 days at 500°F., after which the Portland cement lost 33% of its weight while thecalcium aluminate cement gained 9.1% in weight.

Calcium aluminate (Lehigh "REFCON™") was mixed with 59% by weight waterand cured for 24 hours at 500° F. The same calcium aluminate was mixedwith ASTM class F fly ash in an amount of 75% by weight of the calciumaluminate and with water in an amount of 34% by weight of calciumaluminate and cured for 24 hours at 500° F. The set samples were testedfor compressive strengths in accordance with the above mentioned APISpecification 10. The set sample formed with calcium aluminate alone hada compressive strength of only 410 psi while the sample formed withcalcium aluminate and fly ash had a compressive strength of 2120 psi.

Thus, the present invention is well adapted to carry out the objects andattain the ends and advantages mentioned as well as those which areinherent therein. While numerous changes may be made by those skilled inthe art, such changes are encompassed within the spirit of thisinvention as defined by the appended claims.

What is claimed is:
 1. An improved cement composition useful incementing high temperature wells containing carbon dioxide consistingessentially of:calcium aluminate present in an amount in the range offrom about 15% to about 45% by weight of said composition; ASTM Class Ffly ash present in an amount in the range of from about 25% to about 45%by weight of said composition; sufficient water to form a pumpableslurry; a foaming agent comprising an alpha-olefinic sulfonate havingthe formula

    H(CH.sub.2).sub.n --CH═CH--(CH.sub.2).sub.m SO.sub.3 Na

wherein n and m are integers in the range of from about 6 to about 16,said foaming agent being present in an amount in the range of from about1.0% to about 2.0% by weight of the water in said composition; and afoam stabilizer comprising a betaine having the formula

    R--CONHCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub.2 CH.sub.2 CO.sub.2.sup.-

wherein R is a radical selected from the group of decyl, cetyl, oleyl,lauryl and cocoyl, said foam stabilizer being present in an amount inthe range of from about 0.5% to about 1.0% by weight of the water insaid composition.
 2. The composition of claim 1 wherein saidalpha-olefinic sulfonate is sulfonic acid C₁₆₋₁₆ alkane sodium salt. 3.The composition of claim 1 wherein said betaine iscocoylamidopropylbetaine.
 4. An improved cement composition useful incementing high temperature wells containing carbon dioxide consistingessentially of:calcium aluminate present in an amount in the range offrom about 15% to about 45% by weight of said composition; ASTM Class Ffly ash present in an amount in the range of from about 25% to about 45%by weight of said composition; ground rubber particles present in anamount in the range of from about 10% to about 40% by weight of saidcomposition; sufficient water to form a pumpable slurry; a foaming agentpresent in an amount effective to facilitate foaming; a foam stabilizerpresent in an amount effective to stabilize a foam; and a gas present inan amount sufficient to form a foam having a density in the range offrom about 9.5 to about 14 pounds per gallon.
 5. The composition ofclaim 4 wherein said water is selected from the group of fresh water andsalt water.
 6. The composition of claim 4 wherein said water is presentin said composition in an amount in the range of from about 20% to about50% by weight of said composition.
 7. The composition of claim 4 whichfurther consists essentially of a set retarder selected from the groupof gluconic acid and citric acid.
 8. The composition of claim 4 whereinsaid foaming agent comprises an alpha-olefinic sulfonate having theformula

    H(CH.sub.2).sub.n --CH═CH--(CH.sub.2).sub.m SO.sub.3 Na

wherein n and m are integers in the range of from about 6 to about 16,said foaming agent being present in an amount in the range of from about1.0% to about 2.0% by weight of the water in said composition.
 9. Thecomposition of claim 4 wherein said foam stabilizer comprises a betainehaving the formula

    R--CONHCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub.2 CH.sub.2 CO.sub.2.sup.-

wherein R is a radical selected from the group of decyl, cetyl, oleyl,lauryl and cocoyl, said foam stabilizer being present in an amount inthe range of from about 0.5% to about 1.0% by weight of the water insaid composition.
 10. The composition of claim 4 wherein said gas isselected from the group of nitrogen and air.
 11. A light weight wellcement composition useful in cementing high temperature wells containingcarbon dioxide comprising:calcium aluminate present in an amount ofabout 28% by weight of said composition; sodium polyphosphate present inan amount of about 19% by weight of said composition; ASTM class F flyash present in an amount of about 49% by weight of said composition;sufficient water to form a pumpable slurry; a foaming agent present inan amount effective to facilitate foaming; a foam stabilizer present inan amount effective to stabilize a foam; and a gas present in an amountsufficient to form a foam having a density in the range of from about9.5 to about 14 pounds per gallon.
 12. The composition of claim 11wherein said foaming agent is a sulfonic acid C₁₆₋₁₆ alkane sodium saltand is present in an amount of about 2% by weight of said composition.13. The composition of claim 11 wherein said foam stabilizer iscocoylamidopropylbetaine and is present in an amount of about 1% byweight of said composition.
 14. The composition of claim 11 whichfurther comprises ground rubber particles present in an amount in therange of from about 10% to about 40% by weight of said composition. 15.The composition of claim 11 which further comprises a set retarderselected from the group of gluconic acid and citric acid.
 16. A methodof cementing a subterranean zone containing carbon dioxide penetrated bya well bore comprising the steps of:(a) forming a well cementcomposition consisting essentially of calcium aluminate, ASTM Class Ffly ash, sufficient water to form a pumpable slurry, a foaming agentcomprising an alpha-olefinic sulfonate having the formula

    H(CH.sub.2).sub.n --CH═CH--(CH.sub.2).sub.m SO.sub.3 Na

wherein n and m are integers in the range of from about 6 to about 16,said foaming agent being present in an amount in the range of from about1.0% to about 2.0% by weight of the water in said composition, a foamstabilizer comprising a betaine having the formula

    R--CONHCH.sub.2 CH.sub.2 N.sup.+ (CH.sub.3).sub.2 CH.sub.2 CO.sub.2.sup.-

wherein R is a radical selected from the group of decyl, cetyl, oleyl,lauryl and cocoyl, said foam stabilizer being present in an amount inthe range of from about 0.5% to about 1.0% by weight of the water insaid composition and a gas present in an sufficient to form said foamhaving a density in the range of from about 9.5 to about 14 pounds pergallon; (b) pumping said cement composition into said subterranean zoneby way of said well bore; and (c) allowing said cement composition toset into a hard impermeable mass therein.
 17. The method of claim 16wherein said water is selected from the group of fresh water and saltwater.
 18. The method of claim 16 wherein said calcium aluminate ispresent in said composition in an amount in the range of from about 15%to about 45% by weight of said composition.
 19. The method of claim 16wherein said fly ash is present in said composition in an amount in therange of from about 25% to about 45% by weight of said composition. 20.The method of claim 16 wherein said alpha-olefinic sulfonate is sulfonicacid C₁₆₋₁₆ alkane sodium salt.
 21. The method of claim 16 wherein saidbetaine is cocoylamidopropylbetaine.
 22. A method of cementing a hightemperature subterranean zone containing carbon dioxide penetrated by awell bore comprising the steps of:(a) forming a light weight well cementcomposition comprised of calcium aluminate, sodium polyphosphate, flyash, sufficient water to form a pumpable slurry, a foaming agent, a foamstabilizer and a gas present in an amount sufficient to form a foamhaving a density in the range from about 9.5 to about 14.0 pounds pergallon; (b) pumping said cement composition into said subterranean zoneby way of said well bore; and (c) allowing said cement composition toset into a hard impermeable mass therein.
 23. The method of claim 22wherein said water is selected from the group of fresh water andsaltwater.
 24. The method of claim 22 wherein said foaming agent is analpha-olefinic sulfonate.
 25. The method of claim 24 wherein saidalpha-olefinic sulfonate is a sulfonic acid C₁₆₋₁₆ alkane sodium saltand is present in said composition in an amount in the range of fromabout 1% to about 2% by weight of water in said composition.
 26. Themethod of claim 22 wherein said foam stabilizer is a betaine.
 27. Themethod of claim 26 wherein said betaine is cocoylamidopropylbetaine andis present in said composition in an amount in the range of from about0.5% to about 1% by weight of water in said composition.
 28. The methodof claim 22 wherein said calcium aluminate is present in saidcomposition in an amount in the range of from about 15% to about 45% byweight of said composition.
 29. The method of claim 22 wherein saidsodium polyphosphate is present in said composition in an amount in therange of from about 5% to about 20% by weight of said composition. 30.The method of claim 22 wherein said fly ash is present in saidcomposition in an amount in the range of from about 25% to about 45% byweight of said composition.
 31. The method of claim 22 wherein saidcomposition further comprises ground rubber particles present in anamount in the range of from about 10% to about 40% by weight of saidcomposition.